单颗粒煤燃烧过程中周围碳烟浓度分布特性研究

Study on the Transient Distribution Characteristics of Soot Concentration Around Isolated Coal Particles

通过分析"实践十号"卫星长时间微重力下单颗粒煤燃烧实验的彩色和红外图像,获得了单颗煤粒在各向同性燃烧条件下周围碳烟辐射强度分布,同时使用瞬态燃烧模型对实验进行模拟,进一步揭示了煤颗粒周围的碳烟浓度分布规律及其控制因素。实验和模型研究表明,2 mm煤颗粒在(1.5~7)_(r0)处存在碳烟。挥发分燃烧中期,当氧气质量分数低于8%且气体温度高于1400 K时,颗粒周围的碳烟辐射强度和体积分数沿径向均呈双峰分布,而常重力下实验受自然对流影响呈现单峰分布。

The transient distribution of soot radiation intensity around isolated coal particles burning under the condition of isotropy is obtained by processing and analyzing the color and infrared images of the long-term microgravity combustion experiment carried out on the SJ-10 satellite.Meanwhile,a transient model with consideration of soot evolution of isolated coal particles is developed to further reveal the distribution of soot volume fraction around coal particles and corresponding controlling factors.Both the experimental and modelling results indicate that the soot concentration is distributed radially from 1.5 to 7 times the particle radius and varies nonmonotonously for coal particles with a diameter of 2 mm.In the mid-stage of volatile combustion,when the oxygen mass fraction is lower than 8%and the gas temperature is higher than 1400 K,the radiation intensity and volume fraction of soot around the particles are evolved a double-peak distribution along the radial direction,while the experiments conducted under normal gravity present a single-peak distribution due to the oxygen replenishment by natural convection.